"The truth. I just want to hear the truth from him," Tracy Martin said today on " Good Morning America." "I would ask him, why Trayvon, and why couldn't he have just stayed in his vehicle like the dispatcher instructed him to do."

Zimmerman, 28, was charged Wednesday in the Feb. 26 shooting death of Martin, a black teenager, as he walked to the home of his father's fiancée in the same gated Sanford, Fla., community where Zimmerman lived and served as a neighborhood watch captain.

Zimmerman, a white Hispanic, called 911 to report Martin, a black teenager, as a suspicious person. The 911 dispatcher told Zimmerman he didn't need to follow Martin.

Zimmerman left his truck and, in a confrontation, Martin was shot and killed.

Martin's girlfriend was on the phone with him in the moments before he was shot and told ABC News that he was being followed and she urged him to run.

Zimmerman claims he got out of the vehicle so he could read a house number and tell the 911 dispatcher where he saw Martin, but while returning his truck, Martin knocked him down, banged his head on the ground and went for his gun. He claims he shot Martin in self defense.

"We've always believed that once the evidence was examined properly that we would receive a call letting us know that there would be some charges brought against Zimmerman," Tracy Martin said today.

The charge was announced Wednesday by special prosecutor Angela Corey at a news conference in Jacksonville. If convicted of the charges Zimmerman could face a maximum sentence of life in prison.

"I was overwhelmed," Martin's mother, Sybrina Fulton said after explaining that Corey called the family in advance of her public announcement of the charge against Zimmerman. "We have a sense of peace right now because we know that the person that shot and killed our son will be held accountable for it."

Fulton and Martin have been critical of the way the case was handled by the Sanford police and had campaigned for Zimmerman to be arrested and charged. They have said they believe their son was racially profiled and that the murder was a hate crime.

Zimmerman and his supporters say that the shooting had nothing to do with race and that he shot Martin in self-defense.

The charges are certain to provoke controversy in Sanford, Fla., where the shooting took place, and across the country.

The shooting has become a national touchstone over race, with the Martin family's case championed by civil rights leaders like Al Sharpton and Jesse Jackson, Jr., an online petition calling for Zimmerman's arrest and rallies held in cities across the country.

"We're just thankful for all of those people who really helped out, the churches, the clergy, the college students, the law firms," Fulton said. "We just really appreciate so much for so many people to reach out to us and let us know that we are not alone."

On "GMA," the attorney representing Martin's family asked for calm.

"Tracy and Sybrina and his [Trayvon's] family have all asked for an arrest so it can go before a judge and jury and everyone can make sure it's fair, and they can accept the rule of law," said the attorney, Benjamin Crump. "We want everyone else to be peaceful and calm and accept the rule of law here."

Zimmerman's new attorney, Mark O'Mara, who took the case late Wednesday after Zimmerman's previous attorneys resigned, made a similar plea for his own client.

"I'm hoping things will calm down and the community will truly let us do our jobs, both the prosecutor and me, to try and get this case tried fairly and only in front of the jury and not on TV or on the streets," he said on "GMA."

O'Mara said his client will plead not guilty and that he would seek his release on bond in his first court appearance today.